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Suspension Ride Frequency & Rebound Ratio Calculator

Vehicle suspension design requires balancing spring stiffness and shock absorber damping to isolate road roughness while controlling body heave, pitch, and roll.

Coil spring stiffness rate.

Wheel displacement divided by spring displacement (typically 0.7 to 1.0).

Total scale mass supported at this wheel corner.

Weight of wheel, tire, brake rotor, caliper, and hub assembly.

Damping ratio zeta (0.60–0.70 for passenger cars, 0.65–0.85 for racecars).

Percentage of total damping allocated to rebound vs. compression (typically 65% - 80%).

Calculated Result
1.55 Hz

Corner Ride Frequency (f_n)

Natural Ride Frequency

1.55 Hz

Wheel Rate (K_w)

28.9 N/mm (28,900 N/m)

Installed Spring Rate

40 N/mm

Corner Sprung Mass

305 kg

Critical Damping (C_c)

5,938 N·s/m

Total Wheel Damping (C)

3,860 N·s/m (ζ = 0.65)

Rebound Damping Force

5,403 N·s/m (70% split)

Bump/Compression Damping

2,316 N·s/m (30% split)

Ride Classification

Sport Sedan / Hot Hatch (1.5 - 1.8 Hz)

Calculation Breakdown

  1. Wheel Rate from Motion RatioK_w = K_spring · MR² = 40 N/mm · (0.85)² = 28.9 N/mm (28,900 N/m).
  2. Corner Sprung MassM_sprung = M_corner (350 kg) - M_unsprung (45 kg) = 305 kg.
  3. Natural Frequency Calculationf_n = (1 / 2π) · √(K_w / M_sprung) = (1 / 6.283) · √(28,900 / 305) = 1.55 Hz.
  4. Critical Damping & SplitC_c = 2·√(K_w · M_c) = 5,938 N·s/m. Rebound split: 5,403 N·s/m, Bump: 2,316 N·s/m.

Suspension Dynamic Properties

Interactive visualization based on your current inputs

Value
0.016334965Freq (Hz × 10)Wheel Rate (N/mm)Spring Rate (N/mm)Damping Ratio (ζ × 100)ParameterValue

What Is the Suspension Ride Frequency & Rebound Ratio Calculator?

The Suspension Ride Frequency & Rebound Ratio Calculator sizes automotive springs and dampers to match vehicle dynamic targets.

How Does the Suspension Ride Frequency & Rebound Ratio Calculator Work?

Converts installed spring rate through the suspension motion ratio to determine effective wheel rate and harmonic ride frequency.

Suspension Ride Frequency & Rebound Ratio Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

K_w = K_s \cdot MR^2, \quad f_n = \frac{1}{2 \pi} \sqrt{\frac{K_w}{M_{sprung}}}, \quad C_c = 2 \sqrt{K_w \cdot M_{sprung}}

Models vehicle quarter-car suspension dynamics to achieve targeted chassis ride frequencies.

How to Use the Suspension Ride Frequency & Rebound Ratio Calculator

  1. Enter spring stiffness and suspension geometry motion ratio.
  2. Specify corner scaled weight and unsprung wheel weight.
  3. Adjust damping ratio and rebound/bump split to optimize grip and comfort.

Step-by-Step Example Calculation

Sport Sedan Front Suspension Tuning

Input Values:

springRate:40
motionRatio:0.85
cornerWeight:350
unsprungWeight:45
dampingRatio:0.65
reboundSplitPercent:70
Worked Steps: Delivers a 1.55 Hz natural frequency with 28.9 N/mm effective wheel rate.

Understanding Your Result

Natural Ride Frequency (Hz): 1.0–1.5 Hz for comfort, 1.5–2.0 Hz for performance, >2.2 Hz for aero racecars.

Wheel Rate: Effective stiffness felt at the tire contact patch.

Damping Split: Rebound vs. bump damping forces.

Factors That Affect the Result

  • Motion ratio squares the effect on wheel rate (MR²), so even slight linkage angle shifts alter wheel stiffness significantly.

When Should You Use This Calculator?

  • Coilover setup tuning, track day chassis setup, and FSAE racing suspension development.

Assumptions & Limitations

  • Quarter-car model neglecting tire vertical compliance and anti-roll bar roll stiffness.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard vehicle dynamics formulation per Milliken & Milliken.

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